Engine ignition and power testing



Sept. 20, 1949. R. L. SEX'R-DN, Re. 23,150

ENGINE IGNITION AND POWER TESTING APPARATUS Original Filed April 16, 1945 2 Sheets-Sheet l METER iNVENTOR 5.5 T L SEIXTON 25 I ATTORNEY Sept. 20, 1949. R. L. SEXTON ENGINE IGNITION AND POWER TESTING APPARATUS 2 Sheets-Sheet 2 Original Filed April 16, 1945 INVENTOR Pol 359T .L. SEA TQ/V ATTORNEY Related Se t. 20, 1949 I 'Re. 23,150

ENGINE IGNITION AND POWER TESTING APPARATUS Robert L. Sexton,'Port Washington, N. Y., as-

sgfigr to John EJJndberg, Jr., Redwood City,

Original No. 2,445,245, dated July 13, 1948, Serial No. 588,565, April 16, 1945. Application for reissue June 9, 1949. Serial No. 98,071

4 Claims. 1

This invention relates generally to internal combustion engine testing'apparatus, and the invention has reference more particularly to a novel aircraft engine ignition and cylinder power 2 button determine whether or not the ignition in that cylinder is faulty. In the event of dual ignition, the pressure of two buttons will determine whether .or not the ignition of the cylinder testing apparatus. 5 is faulty, whereupon the pressing of the two It is extremely important in modern internal buttons alternately will determine which plug combustion engines, and especially aircraft enin such cylinder is faulty, so that an airplane zines, that the same be kept operating efficiently operator is able to note, even while in flight, and with as short shutdowns for repairs as poswhich of the thirty-six plugs in an eighteensible. The investment in modern large airplanes l0 cylinder engine is faulty by merely pressing butis so great that it is necessary to keep the planes tons, thereby enabling the replacement of a in the air approximately seventy per cent of single defective plug without replacing eighteen the time in order to recoup the investment made plugs. in the airplane, and hence it becomes very im- A further feature of the present invention is portant that engine overhaul periods be shortto provide test equipment for checking on the ened as much as possible. torque and power output of any desired cylinder When it is realized that ignition troubles are of an engine, for example, if it happens to be the cause of more engine failures than any other an eighteen-cylinder engine, the engine operator factor, the importance of easily detecting and may select any cylinder and determine its torque locating ignition troubles becomes very apparent. and power output. In that way he readily deter- The present methods of shooting ignition trouble mines whether a cylinder is performing properly, are arduous and consume considerable time. For and thereby foretell failures. example, assuming an eighteen-cylinder aircraft Very often, a cylinder will gradually fall ofl? engine is rough on the left magneto," which in power, and this may be true of a number of would tend to indicate that a rear plug is fouled, cylinders, so that the overall power of the engine in that case, under the present system of testfalls off and yet the trouble is not sufficiently -ing, eighteen spark plugs are usually changed, bad to warrant complete overhaul of the engine. where actually only one plug is at fault. This By using the test equipment of the present in- ;makes ignition repair work on airplane engines vention, any cylinder or cylinders falling off in not only a lengthy matter, but also expensive. 80 power can be quickly detected and correction Furthermore, cylinders very often fall off in made. Furthermore, detonation resulting in loss ,power, and up to the time of this invention it of power can be detected and located.

was impossible to determine readily just which A further feature of the present invention is cylinder was falling off in power and to what to provide a small, inexpensive, compact, and extent. Furthermore, faulty ignition results in a light test equipment that is readily applied to local radio interference, which is highly objecexisting engine installations, and is easily oper- ,tionable, especially in aircraft. ated for testing and locating ignition troubles The applicant hereof has discovered means and defective cylinders. even while the engine whereby the ignition of any one selected cylinder is running, thereby greatly decreasing the mainmay be isolated, so to speak. even while the tenance time heretofore required inservicing air- U engine is running, and tested for faulty action. planes and cutting the cost of maintenance enorv,In the event of .such faulty action, it is known mously.

definitely just where the trouble lies, so that Other features and advantages will become careful and tedious examination ofall spark apparent from the specification, taken in conplugs in all cylinders is unnecessary. 46 nection with the accompanying drawings wherein An important feature of the present inven-- the invention is embodied in concrete form. ,tion is to provide novel engine ignition and In the drawings, I

power testing apparatus which enables the en- Y Fig. 1 is a schematic View of the novel engine gine operator "to select any cylinder in which ignition apparatus of this invention shown as he is interested and then by merely pressing a 50 applied to atom-cylinder engine;

"imp

Referring now to the drawings, the reference numeral designates a contact breaker cam of the engine magneto which. as shown .in Fig. 1A, maybemagnetolor I. Thecamiisadapted to actuate the breaker arm I for opening and closing the contact breaker points I located in the circuit of the primary winding It of the magneto. As is customary, when the primary contact points 9 open, the flow of primary current through coil III is interrupted, causing'an extremely rapid change in flux linkages, resulting in the production of a high voltage in the secondary winding i I of the magneto, which voltage is supplied through lead H to the distributor finger II for e through distributor contacts I, 2, I, and 4 and connected high tension leads II, II, It, and H to engine spark plugs l', 2', 3', and 4'. So far the structure is typical of an engine ignition system.

In its preferred form, the apparatus of the present invention is an attachment comprising anauxiliary cam shaft it having an enlarged hollow inner end portion I! which fits within a recess provided in the outer end of the magneto breaker cam 5 (see Fig. 2), the said auxiliary shaft 18 having a driving block or key 20 adapted to fit into a slot provided in the end of the contact breaker cam 5, whereby this breaker cam drives the auxiliary cam shaft l8.

Shaft I8 is mounted on a rotor-bearing block 22 which abuts the enlarged end portion i8. Bearing block 22 is longitudinally slidable in slide-bearing aperture 23 provided in a bell housing 24. A screw 25 extends through housing 24 and projects into a longitudinal groove 26 in rotor bearing 22, thereby serving to prevent the turning of this hearing while permitting longitudinal movement thereof. A coil compression spring 21 presses on the rotor-bearing block 22 and hence urges the enlarged end portion is of shaft is inwardly toward and into engagement continuously with the contact breaker cam I to be driven by the latter.

The enlarged portion I! of auxiliary cam shai' II is provided with a peripheral longitudinal cam groove or depression 28 (see especially Fig. 4) which cooperates with a cam follower 28 that serves to actuate a pair of breaker points It. So long as the follower 28 is riding on the high surface 28' of the cam shaft portion it, the follower 28 holds the breaker points Ill disengaged by flexing arm 3! upwardly. However, when the cam groove 28 rides under the follower'n, this follower drops down into groove 2| and allows the resilient arm ii to move downwardly, thereby engaging points or contacts 3. as shown in Fig. 4. These breaker points are connected at one side (see Fig. 1) through a lead 32, condenser ll, push-button 34, and lead II to one side of the primary winding it. The other side of the breaker points are connected by lead It to ground.

Thebellhousing 24isshownonitsexterior surface provided with numerals I, I, 8 and 4 (see Fig. 3) corresponding to the number of cylinders shown in the structure of Fig. 1, wherein a fourcylinder engine is involved, which numerals correspond to and are arranged in the firing order of the engine cylinders. The open mouth of this bell housing fits into a circular depression 31 provided in a plate It attached to the end of the magneto housing 3!. The bell housing has a radial lip or fiange 4| that is engaged by springpressed washers 4! carried by screws 42, which serve to retain the open mouth portion of the bell housing in assembled relation with the plate II and rotatable with respect to this plate. An index member or pointer 42 is carried by the plate 38 for cooperating with the marks i, 2, I and 4 on the periphery of the bell housing 24.

Obviously, if the engine had eighteen cylinders,.

there would be eighteen numbers on the bell housing 24.

An outer end cover or knob 44 is fixedly mounted upon the bell housing 24 and has a knurled outer surface 45 which may be grasped for turning this bell housing so that any particular cylinder number, such as I, may be aligned with the pointer 43 as shown in Fig. 3. With such position of the bell housing, the cam follower 2! is so positioned angularly with respect to the contact breaker cam 5 and cam groove 28 of the auxiliary cam that when cylinder l of the engine fires, the cam follower 29 will drop into cam slot 28, thereby closing contact points 30 at the very moment that the spark plug in cylinder I fires. However, this action has no effect so long as the push-button 34 is open. If push-button 34 is held closed, then every time cylinder I is about to fire both sides of the primary winding no will be grounded because (referring particularly to Fig. l) with the contact points 3!! closed and switch 34 closed, the lower side of the primary winding Iii, as shown in Fig. 1, is grounded and its other side is always grounded, and so no voltage is induced in the secondary H and consequently the plug or cylinder I will receive no secondary current and hence will not fire.

Likewise, if the knob 44 is turned so as' to bring the number 2 on bell housing 24 opposite pointer 43, then each time that cylinder number 2 fires, the contact points 30 will be closed, and if the push-button 34 is also closed at that time, the plug or cylinder number 2 will not fire since both sides of the primary winding I0 areshorted.

When applying the device to a dual-ignition engine as shown in Fig. 1A, two sets of contact points 30 and 30' are employed and likewise two push-buttons 84 and 34' are employed, leads 35 and 35' connecting to the primary winding of the two magnetos land I.- only two high tension leads of these two magnetos are shown in Fig. 1A connected to a single cylinder, but it will be understood that leads are connected to each of the cylinders. A switch 46 is shown for permanently grounding the primary iii of the magneto when desired. In Fig. 1A, the auxiliary cam shaft II is shown driven directly from the engine through reduction gearing 56 instead of from the magneto.- A torque meter is attached to the engine to indicate the brake mean effective pressure (B. M. E. P.) or the pressure component of torque in pounds per square inch. This torque meter is illustrated as comprising a sun gear 48, which is attached by linkage 48 to a plunger 50 working within hydraulic cylinder 5| which is supplied with oil under pressure by pump 52, and agauge ",whichmayreaddirectlyin torque units, if desired, is connected to the cylinder ii. A pinion 54 meshes with the sun gear ll and with the propeller drive gear 55 so that the torque applied to the propeller is transmitted through pinion i4 and gear 48 to plunger 50, whereby meter 53 reads the torque of the engine or may be calibrated in pressure units, if desired. From the reading of meter I3, the brake horsepower of the engine can be readily calculated as follows:

to determine whether or not the spark plug of a cylinder is functioning properly, it is merely necessary to turn the knob 44 until the desired cylinder number, such as number 1, is opposite the index 43 as shown in Figs. 1 and 3. The brake mean eil'ective pressure (B. M. E. P.) is read from the torque meter 53. The push-button 34 shown .in Fig. 1 is then depressed'so as to ground both sides of the primary l0, thereby shutting off the high tension power to the plug of cylinder l. The B. M. E. P. reading of meter 53 is again noted during the ignition cutout of cylinder i. The difference between the first B. M. E. P. reading and the second represents the loss in torque, which can be converted to horsepower as follows:

Lost B. M. E. RXR. P. M.

R B. H. P. lost wherein represents the engine factor which does not change.

For a good cylinder the value of B. H. P. lost should equal B. H.P. K

plug only, by closing switch I4 alone. If new the B. M. E. B. does fall ofl, the rear plug has faulty ignition, and if the B. M. E. P. does not fall, the rear plug and ignition is all right. The

push-buttom 34' is now closed, thereby grounding the'rear plug, and the same procedure is repeated,

' is at fault as well as the particular plug which is faulty.

In making power tests, the engineer will pre both buttons 34 and 34' simultaneously and note the B. M. E. P. drop, thereby determining the power output oi any particular cylinder by the change in B. M; E. P. reading. By pushing the button 34, controlling the front plug, we can test the rear plug ignition, and by pushing the button 84', controlling the rear plug, we can test the front plug ignition.

The apparatus of this invention also serves for determining the location of faulty ignition causing radio interference. Where a dual-ignition system is employed, each magneto is grounded in turn by closing switches 46 and 46' in succession. By grounding switch 46, if the interference ends, it is known that the ignition trouble is in the system associated with switch 48. If the troubl still persists, then it is the ignition system associated with switch 46'. Each plug of the faulty ignition system is then grounded in turn to determine which plug is faulty. The connections to this plug are then checked as well as the plug to detect loose connections. Thus, it will be seen that merely by pressing buttons 34 and 34' the engineer can quickly determine which cylinder of a multi-cylinder engine is not functioning properly and then readily locate the plug of that particular portion of the ignition system which is at fault, thereby enabling the replacement oi one plug instead of many plugs and eliminating the hunt and try methods at present employed. Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made gineer can turn the knob 44 to successive cylinder numbers and press the button 34 and read the meter 53.

Where dual ignition is used, as shown in Fig. 1A, to locate the cylinders having faulty ignition, both buttons 34 and 34' are pressed or closed simultaneously, thereby grounding the corresponding plugs of cylinder l, for example, simultaneously, whereupon the fall in B. M. E. P. is noted. If no fall is indicated, obviously no power is being received from that cylinder, which indicates any one or more of the following diihculties:

a. Poor compression,

11. Both spark plugs fouled simultaneously (very rare),

0. Mixture not reaching cylinder,

d. Spark plug wires broken or not hooked to plugs.

Assuming that the B. M. E. P. does fall to some extent when both plugs are grounded, the next step is to ground one plug, for example, the front without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. Engine and ignition power testing apparatus comprising an auxiliary cam driven from the engine, contact points actuated by said auxiliary cam, a housing for carrying said contact points, said housing being angularly adjustable with re spect to said auxiliary cam to thereby effect the closing of said contact points simultaneously with the firing of any selected engine cylinder, a circuit connecting the engine ignition through said contact points to ground, switch means insaid circuit for closing said circuit to cut off the ignition of such selected cylinder, and a torque indicator operable from the engine, for showing changes in the torque output of the engine responsive to the operation of said switch means.

2. In apparatus of the character described for testing of engine cylinders, contact means connected at one side with the engine ignition and at the other side with ground, adjustable means for setting said contact means for operation in synchronism with the firing of any selected engine 1 cylinder. whereby the ignition of such cylinder is cut out when desired. and a torque meter attached to the engine tor indicating change in engine torque with the cutting out of the ignition 0! such selected cylinder.

3. Apparatus for shutting oil. the supply of high tension current to engine spark plugs during engine operation comprising a grounding circuit electrically connected with the spark plu s. said circuit comprising make and break contact members actuated from the engine and switch means for completing said circuit, means for adjusting said contact members for causing actuation of the same in synchronism with the firing of any selected spark plug. whereby the closing of said switch means serves to shut oi! the current to the spark plug selected. and a torque meter driven irom the engine for indicating change in engine torque upon the closing of said switch means.

4. In apparatus of the character described for go testing of engine cylinders. ignition short circuiting means connected at one side with the ignition and at the other side with ground. adjustable means for setting said ignition short circuiting means for operation in synchronism with the tiring of any selected engine cylinder. whereby the ignition of such cylinder is cut out when desired, and a torque meter attached to the engine ior indicating change in engine torque with the cutting out of ignition 0! such selected cylinder.

ROBERT L. SEXION.

REFERENCES CITED Thoiollowingreierencesareotrecordinthe iileotthispatent:

UNITED STATES QATENTB Date Number Name 1,639,803 Gowland Aug. 16, 1927 1 2,274,088 Morrison Feb. 24, 1942 FOREIGN PATENTS Number Country Date 139,829 Great Britain Mar. 18, 1920 

